In the past, IE used a custom algorithm and kept a private list of domain name parsing exceptions. Owners of domain names that needed exception handling by our algorithm had to notify Microsoft that exception parsing was required.

Going forward, to increase interoperability we are switching our parsing to use the algorithms and domain list found at http://www.publicsuffix.org, which is a cross-vendor initiative also used by other browsers. Starting with the Windows 10 Technical Preview, IE will parse domain names in a more interoperable manner. After this change has been released in a product release you will no longer need to notify Microsoft of special domain names; we will automatically pick up and include the changes made at publicsuffix.org on a regular cadence. We are also evaluating bringing this change downlevel to accelerate the transition.

Brenno: there is as yet no feasible replacement for publicsuffix.org. As long as Microsoft implement the algorithm correctly (i.e. if they see a domain that's not in the list, treat it like .com – i.e. flat namespace) then it's not a massive disaster if new gTLDs take a little while to percolate into the system, because most of them are flat like that anyway.

Thanks Gerv. Yeah, from a security standpoint the possibly slow percolating (smartphones/tablets?) is certainly not going to be a problem. It might be a bit of a challenge to those companies getting their own TLD but maybe it serves them right. 😀